hydrated_bloc 2.0.0
An extension to the bloc state management library which automatically persists and restores bloc states.
Overview #
hydrated_bloc
exports a HydratedStorage
interface which means it can work with any storage provider. Out of the box, it comes with its own implementation: HydratedBlocStorage
.
HydratedBlocStorage
is built on top of path_provider for a platform-agnostic storage layer. The out-of-the-box storage implementation reads/writes to file using the toJson
/fromJson
methods on HydratedBloc
and should perform very well for most use-cases (performance reports coming soon). HydratedBlocStorage
is supported for desktop (example).
In addition, while the HydratedBlocStorage
client doesn't automatically encrypt/decrypt the data, it is fairly straightforward to implement a custom HydratedStorage
client which does support encryption.
Usage #
1. Use HydratedBlocDelegate
void main() async {
// https://github.com/flutter/flutter/pull/38464
// Changes in Flutter v1.9.4 require you to call WidgetsFlutterBinding.ensureInitialized()
// before using any plugins if the code is executed before runApp.
// As a result, you may have to uncomment the following line if you're using Flutter >=1.9.4.
//
// WidgetsFlutterBinding.ensureInitialized();
BlocSupervisor.delegate = await HydratedBlocDelegate.build();
runApp(App());
}
2. Extend HydratedBloc
and override initialState, fromJson and toJson methods
class CounterBloc extends HydratedBloc<CounterEvent, CounterState> {
// Use previously cached initialState if it's available
@override
CounterState get initialState {
return super.initialState ?? CounterState(0);
}
// Called when trying to read cached state from storage.
// Be sure to handle any exceptions that can occur and return null
// to indicate that there is no cached data.
@override
CounterState fromJson(Map<String, dynamic> source) {
try {
return CounterState(source['value'] as int);
} catch (_) {
return null;
}
}
// Called on each state change (transition)
// If it returns null, then no cache updates will occur.
// Otherwise, the returned value will be cached.
@override
Map<String, int> toJson(CounterState state) {
try {
return { 'value': state.value };
} catch (_) {
return null;
}
}
@override
Stream<CounterState> mapEventToState(CounterEvent event) async* {
switch (event) {
case CounterEvent.decrement:
yield CounterState(state.value - 1);
break;
case CounterEvent.increment:
yield CounterState(state.value + 1);
break;
}
}
}
enum CounterEvent { increment, decrement }
class CounterState {
int value;
CounterState(this.value);
}
Now our CounterBloc
is a HydratedBloc
and will automatically persist its state. We can increment the counter value, hot restart, kill the app, etc... and our CounterBloc
will always retain its state.
Custom Storage Directory #
By default, all data is written to temporary storage which means it can be wiped by the operating system at any point in time.
An optional storageDirectory
can be provided to override the default temporary storage directory:
BlocSupervisor.delegate = await HydratedBlocDelegate.build(
storageDirectory: await getApplicationDocumentsDirectory(),
);
Custom Hydrated Storage #
If the default HydratedBlocStorage
doesn't meet your needs, you can always implement a custom HydratedStorage
by simply implementing the HydratedStorage
interface and initializing HydratedBlocDelegate
with the custom HydratedStorage
.
// my_hydrated_storage.dart
class MyHydratedStorage implements HydratedStorage {
@override
dynamic read(String key) {
// TODO: implement read
}
@override
Future<void> write(String key, dynamic value) async {
// TODO: implement write
}
@override
Future<void> delete(String key) async {
// TODO: implement delete
}
@override
Future<void> clear() async {
// TODO: implement clear
}
}
// my_hydrated_bloc_delegate.dart
class MyHydratedBlocDelegate extends HydratedBlocDelegate {
MyHydratedBlocDelegate() : super(MyHydratedBlocStorage());
}
// main.dart
BlocSupervisor.delegate = MyHydratedBlocDelegate();
2.0.0 #
- Update to
bloc ^2.0.0
- Adhere to effective dart
1.1.0 #
- Optional
storageDirectory
can be provided (#28). - Documentation Updates
1.0.0 #
- Update to bloc
v1.0.0
- Documentation Updates
0.8.0 #
- Update to bloc
v0.16.0
- Documentation Updates
0.7.0 #
- Desktop support via path_provider_fde (#24).
- Documentation and Example Updates
0.6.0 #
- Support clearing individual
HydratedBloc
caches (#21) - Documentation and Example Updates
0.5.0 #
- Support for Desktop (#18)
- Documentation and Example Updates
0.4.1 #
- Update to support optional
id
in cases where there are multiple instances of the sameHydratedBloc
- Documentation Updates
0.4.0 #
- Update to bloc
v0.15.0
- Documentation Updates
0.3.2 #
- Minor Updates to Package Dependencies
- Documentation Updates
0.3.1 #
- Add guards to
HydratedBlocStorage
to prevent exception if cache is corrupt.
0.3.0 #
- Update
HydratedBlocStorage
to usegetTemporaryDirectory
instead ofgetApplicationDocumentsDirectory
- Documentation Updates
0.2.1 #
- Bugfix to handle
Blocs
alongsideHydrateBlocs
within the same application. toJson
can returnnull
to avoid persisting the state change
0.2.0 #
- Upated
HydrateBlocDelegate
to have a staticbuild
- Updated
toJson
andfromJson
to eliminate the need to calljson.encode
andjson.decode
explicitly. HydratedBlocSharedPreferences
replaced withHydratedBlocStorage
- Removed dependency on
SharedPreferences
- Documentation Updates
0.1.0 #
- Renamed
HydratedBlocSharedPreferences
toHydratedSharedPreferences
- Documentation Updates
0.0.3 #
Added clear
to HydratedBlocStorage
API and Documentation Updates
0.0.2 #
Documentation Updates
0.0.1 #
Initial Version of the library.
Includes:
HydratedBloc
HydratedBlocDelegate
HydratedBlocSharedPreferences
example #
A new Flutter project.
Getting Started #
This project is a starting point for a Flutter application.
A few resources to get you started if this is your first Flutter project:
For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.
Use this package as a library
1. Depend on it
Add this to your package's pubspec.yaml file:
dependencies:
hydrated_bloc: ^2.0.0
2. Install it
You can install packages from the command line:
with Flutter:
$ flutter pub get
Alternatively, your editor might support flutter pub get
.
Check the docs for your editor to learn more.
3. Import it
Now in your Dart code, you can use:
import 'package:hydrated_bloc/hydrated_bloc.dart';
Popularity:
Describes how popular the package is relative to other packages.
[more]
|
92
|
Health:
Code health derived from static analysis.
[more]
|
100
|
Maintenance:
Reflects how tidy and up-to-date the package is.
[more]
|
90
|
Overall:
Weighted score of the above.
[more]
|
94
|
We analyzed this package on Dec 6, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:
- Dart: 2.6.1
- pana: 0.12.21
- Flutter: 1.9.1+hotfix.6
Platforms
Detected platforms: Flutter
References Flutter, and has no conflicting libraries.
Maintenance issues and suggestions
Support latest dependencies. (-10 points)
The version constraint in pubspec.yaml
does not support the latest published versions for 1 dependency (bloc
).
Dependencies
Package | Constraint | Resolved | Available |
---|---|---|---|
Direct dependencies | |||
Dart SDK | >=2.0.0 <3.0.0 | ||
bloc | ^2.0.0 | 2.0.0 | 3.0.0-dev.1 |
flutter | 0.0.0 | ||
path_provider | ^1.1.0 | 1.4.5 | |
Transitive dependencies | |||
collection | 1.14.11 | 1.14.12 | |
meta | 1.1.7 | 1.1.8 | |
platform | 2.2.1 | ||
rxdart | 0.22.6 | 0.23.0-dev.2 | |
sky_engine | 0.0.99 | ||
typed_data | 1.1.6 | ||
vector_math | 2.0.8 | ||
Dev dependencies | |||
effective_dart | ^1.1.1 | ||
flutter_test | |||
mockito | ^4.0.0 |